There are many existing techniques used for creating documents that are copy- and tamper-resistant. Owners of such documents want to be able to verify that a particular document is an original and has not been copied or altered in any way. Typical examples of such documents are bank cashier's checks, stock certificates, birth certificates, and college transcripts.
One of the “security techniques” used to create such documents is to print a background that consists of two interlaced prismatic patterns of blue and reel ink. These patterns involve very fine lines and color gradients which do not copy or scan well, and a copied document typically will easily be distinguished from an original. Typically this type of printing application requires specialty paper that must be ordered and then securely stored. This paper is then run through a traditional monochrome laser printer to add variable text, such as the data on a printed check.
The specialty paper in many conventional processes is created using an offset printing press, and requires large quantities to be purchased at one time to obtain a lower price. Even in high quantities, this type of paper can be very expensive, in excess of $1.00 per sheet. It should be noted that the security paper industry currently has approximately $3 billion in annual revenue.
Since this is very specialized paper, a security problem is created in that the paper must be stored and accounted for in a manner such that it can not be easily stolen. This requires both inventory space and resources in the security storage area.
FIG. 7 depicts a typical offset printing press in a diagrammatic view, showing the cross-section of the rollers. There are ink rollers that apply ink in a specific manner to a plate cylinder. There are also water rollers that also apply liquid to the plate cylinder. There is an offset cylinder that receives these materials from the plate cylinder and beneath the offset cylinder is an impression cylinder. A nip is created between the offset cylinder and impression cylinder, and the blank paper is sent through the nip and then printed with the duo-tone prismatic pattern.
As can be seen, the “security pattern” created by the plate cylinder is not easily changed using the offset print process. Therefore, it is typical to use the same duo-tone prismatic pattern for a large quantity of paper, to reduce the printing cost. If a pattern is to be changed, then the plate cylinder itself must be changed to accommodate the new pattern. Certainly an individual user or department of most companies could not command a specialized background strictly for that sole user or department.